Ex Situ Heart Perfusion: A Technique to Preserve Isolated Porcine Heart Function

To begin ex-situ perfusion, take an isolated porcine heart. Attach the aorta to a cannula connected to a reservoir via an aortic pump. Massage the ventricles to remove air through the innominate and subclavian aortic branches and then ligate both arteries.

Start the aortic pump at the desired speed. This pump supplies the perfusate - a mixture of isolated porcine heart blood and oxygenated nutrient-rich solution - from the reservoir into the aorta and the aortic root. 

Increase the pump speed to supply the perfusate into the coronary arteries and the coronary sinus, filling the right atrium.  After filling the right atrium, the perfusate drains into the right ventricle and flows through the pulmonary artery as dark deoxygenated blood. This simulates the diastolic phase of the cardiac cycle where the heart is in non-working mode.

Pump the perfusate back from the pulmonary artery to the reservoir. Subsequently, create a left atrial orifice between the pulmonary veins. Attach a cannula connecting it to the reservoir via a pump that regulates atrial pressure. Later, suture the superior vena cava and increase the pump speed, letting the perfusate enter the left atrium. Eventually, the perfusate flows into the left ventricle. 

Ventricular ejection forwards the perfusate through the aorta and returns it back to the reservoir. This recapitulates the systolic phase, completing the heart's cardiac cycle.